Headed firing pin bolt for sensitive percussion fuzes



y 1966 P. KAISER ETAL 3,250,217

HEADED FIRING PIN BOLT FOR SENSITIVE PERCUSSION FUZES Filed Nov. 9, 1964 2 Sheets-Sheet 1 Fig.1 15b 18 /15 /15Cl 17a I //1/ /Z 17 12 l k \\\k l INYENTORS' May 10, 1966 P. KAISER ETAL 3,250,217

HEADED FIRING PIN BOLT FOR SENSITIVE PERCUSSION FUZES Filed Nov. 9, 1964 2 Sheets-Sheet 2 Fig. 2

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United States Patent J 5 Claims. 5:1. 102-76) Sensitive percussion fuzes are conventional particularly for missiles, also those without rifiing. They have a headed firing pin bolt which, when the fuze is in safety state, is retracted so that its head is in the point of the fuze and, on being released, is pushed forward by a compression spring so that it projects beyond the point of the fuze. This takes place after firing and after a delayedaction safety mechanism has run down which holds the compression spring under tension by means of a latch. It is not impossible that, through an exceptonal jolt during transport, the time safety device is accidentally released and the headed firing pin bolt is unintentionally pushed forward into its primed position. Now if a missile is fired with its fuze unintentionally primed in this manner, a

' barrel or premature explosion must be expected which is extremely dangerous both for the weapon and also for the operating crew.

The applicant has already developed a fuze in which the firing pin bolt shaft has at its front end a cup-shaped impact head which in turn is closed on its front side by a widened slip-in cover. Here, in order to show that the firing pin bolt has accidentally moved forward into its primed position, in the event of failure of the time safety device, the impact head and the bolt shaft can be of contrasting colours, so that a wrong position is easily recognizable at sight. If necessary a difference in colour of the two parts .could be seen through a transparent cover.

An optical check is naturally'useless in the dark at night. The applicant has therefore replaced this by a check or control which can be carried out both optically and also by feel, 'so that it will cumstances. The impact head operates like a valve so that in safety position the mushroom of the valve bears on its seat and in primed position is raised therefrom. This can easily be felt and also be seen.

In this manner the problem of watertightness can also be solved satisfactorily at the same time.

Therefore, according to the invention, the slip-in cover of the cup-shaped firing pin bolt head is bevelled around its periphery like a valve mushroom and in retracted safety position rests on the front end flange bevelled like a valve seat on a sleeve pressed forward into the fuze bore, the slip-in cover of the cup-shaped impact head and the sleeve being made of elastic material, preferably synthetic material.

The sleeve carries outside on the frontend flange a reinforcing ring against which an inward beading on the mouth of the fuze bore bears.

In another embodiment of the invention the widened portion of the slip-in cover is made in one piece with the cup-shaped head and carries on its rear side conical sealing spines arranged in the form of a ring and opposite which a packing ring or washer is sunk in the front face of the fuze point, the shank of the firing bolt being resiliently connected with its cup-shaped head. The resilient connection preferably consists of a sleeve firmly screwed on the end of the shank and provided with a front edge flange as counter-bearing for a pressure spring slipped on be noticed under all cirthe sleeve, the rear end of which spring presses against the bottom of the cup-shaped head. The depression in the middle of the cup-shaped head is closed at the front by a preferably inwardly beaded diaphragm.

Two embodiments of the invention are illustrated in longitudinal section in FIGURES 1 and 2 by way of example in the accompanying drawings.

In FIG. 1 the headed firing pin bolt 10 consists of a shank 10b which carries the primer or firing pin 10a at its rear end. It has on its front end in known manner a cup-shaped head 14 which is closed on the front side by a flanged slip-in cover 15. The cover 15 and cupshaped head 14 are connected by a screw bolt 16 passing therethrough. Between the cup 14 and a shoulder in the fuze bore there is a thrust spring 13 surrounding the pin shank 10b. It is maintained under tension and consequently the headed firing pin bolt is held in its retracted safety position by a known latch 12 which is controlled in known manner by the delayed-action safety device.

Now according to the invention the edge of the slip-in cover 15 is bevelled like a valve mushroom at 15b. The slip-in cover 15 is made from elastic, preferably synthetic material.

A bushing 17 is pressed tightly into the point of the fuze from the front end thereof and has at its front end a flange. This flange is bevelled on its front face at 17a and forms a valve seat representing a counter-surface for the bevel 15b of the valve mushroom-shaped slip-in cover 15. The bushing 17 is made from elastic material, for example synthetic substance. The front end flange carries on its outer side a reinforcing ring 18 on to which the mouth edge of the fuze bore is headed over.

'If the headed firing pin bolt 10, 14, 15 is in its retracted safety position, the slip-in cover 15 is on the valve seat 17a of the bushing 17 and forms a Watertight seal for the fuze head.

The sealing effect between the slip-in cover 15 and the valve seat bushing 17 can be improved by providing behind the slip-in cover 15 an annular groove 15a which adds to the resilient effect of the edge of the cover 15.

Now if a defect occurs in the time safety device so that the thrust spring 13 of the firing pin bolt is released prematurely and pushes the bolt forward more or less, the slip-in cover 15 is lifted oif its seat 1711. This can not only be seen but also felt with the fiingers at night, so that a missilewith defective fuze can be thrown out.

In the embodiment illustrated in FIG. 2, the point of the fuze is designated by 51 and the headed firing pin bolt is guided therein with the aid of its shank 10b. It is held in its locked or safety position by the known latch 12 against the action of the thrust spring 13 which is here controlled in known manner by the time safety device. The firing pin bolt has a cup-shaped head 14. This has at its front end an integral widened portion 50 which corresponds to the flange or widening of the slip-in cover 15. This widening 50 has on its rear side several concentric rings of spines 50a. Opposite thereto a packing ring or washer 52 is countersunk in the front face of the fuze point. This packing ring or washer 52 may be made from artificial resin or soft metal, such as lead.

The front end of the firing pin bolt shank 10b extends into the central depression of the cup-shaped bolt head 14. A sleeve 55 is screwed firmly on this front end and has on its front end a flange 55b. A spiral pressure spring -54 is slipped on to the sleeve 55 and bears at its front end against the flange 55b while its rear end presses against the bottom 50b of the central depression of the cup-shaped firing pin bolt head 14. The sealing pressure between the widening 50 and the front face of the fuse point is produced by the thrust spring 54. The cup-shaped head 14 is closed in front by a beaded-in diaphragm 59.

The function of this embodiment as regards the control of the position of the firing pin bolt and the watertightness of the fuze is the same as in the case of the first embodiment.

That which is claimed is:

1. Headed firing pin bolt mechanism for sensitive percussion fuzes comprising a shank having at its front end a cup-shaped head, a slip-in cover to close the front of the head, the slip-in' cover being bevelled on its edge to form a valve surface, a bushing inserted in a fuze bore having a bevelled surface to form a valve seat on the front end thereof, and the slip-in cover and inserted bushing being composed of an elastic material.

2. Headed firing pin mechanism according to claim 1, in which a reinforcing ring is :provided on the outer side of a front end flange of the bushing against which a beaded-in mouth of the fuze bore bears.

3. Headed firing pin mechanism according to claim 1, in which a washer is provided countersunk in a front face of the fuze and the cover is formed in one piece with the cup-shaped head and has on. its rear side concentric rings acting as sealing spines against the washer, and in which the shank of the firing pin bolt is resiliently connected with its cup-shaped head.

4. Headed firing pin mechanism according to claim 1, in which a washer is provided countersunk in a front face of the fuze and the cover is formed in one piece with the cup-shaped head and has on its rear side concentric rings acting as sea-ling spine-s against the washer and in which the shank of the firing pin bolt is resiliently connected with its cup-shaped head, the resilient connection between the firing pin bolt shank, and its cup-shaped head comprising a sleeve firmly screwed on the front end of the shank and is provided with a front edge flange as counter bearing for a compression spring on the sleeve, the rear end of said spring pressing against the bottom of the cup-shaped head.

5. Headed firing pin mechanism according to claim 1, in which a washer is provided countersunk in a front face of the fuze and the cover is formed in one piece with the cup-shaped head and has on its rear side concentric rings acting as sealing spines against the washer, and in which the shank of the firing pin bolt is resiliently connected with its cup-shaped head, a central depression of the cup-shaped head being closed in front by a'beaded-in diaphragm.

References Cited by the Examiner UNITED STATES PATENTS 2/1926 King lO2-84 2/1965 Edmands l0276 

1. HEADED FIRING PIN BOLT MECHANISM FOR SENSITIVE PERCUSSION FUZES COMPRISING A SHANK HAVING AT ITS FRONT END A CUP-SHAPED HEAD, A SLIP-IN COVER TO CLOSE THE FRONT OF THE HEAD, THE SLIP-IN COVER BEING BEVELLED ON ITS EDGE TO FORM A VALVE SURFACE, A BUSHING INSERTED IN A FUZE BORE HAVING A BEVELLED SURFACE TO FORM A VALVE SEAT ON THE FRONT END THEREOF, AND THE SLIP-IN COVER AND INSERTED BUSHING BEING COMPOSED OF AN ELASTIC MATERIAL. 